Pulp product



Patented June 18, 1929.

L I I 1,717,799- UNITED STATES: P -ATENT OFFICE.

ROBERT A. ma, orNoBroLmvmemm.

rum rnonuc'r. I

No Drawing.

In certaincopending applications 1 have de scribed-methods of producing pulp suitable for use as paper pulp, from various raw materials' including porous woods, nonporous woods and other forms of vegetable growths,

v such as cane, bamboos, sedges, straw and vasuch asthose of sodium, magnesium, aluminum',-potass1um, or IIOIl (although the sulfates of chromium, manganese, nickel, cobalt or copper may be used, to some extent) or the chlorids of sodium, potassium, magnesium, calcium, or the nitrates of these, or kainit, or various mixtures of such salts. The strength. of the solution can vary more or less, say between about 1% and 5% and the wood or other vegetable growth is digested in the said liquor, preferably under a pressure of about 80 to 120 lbs, for 1 to 3 hours, after which it is removed from the digestive solution and is preferably soaked in water for a while.

In said processes of my copending cases, the cookingoperation does not convert the chips or pieces ofwood or the like, into a pulp, but merely renders the intercellular cementitious material friable, so that the chips, etc., can be readily mashed or crushed. The cooked product is preferably then crushed (e. g. in a shredder or edge runner or by being passed through heavy rolls) after which it is pulped andbeaten inan ordinary beater for a short time, after which it can be convertedinto paper or sheeted or molded products, either alone or mixed with other kinds of pulp or other additions.

In the last paragraph I have used the term crushed. This term obviously does not include grinding up the wood or other material on a wet grindstone sue-has is commonly used in making ground-wood pulp, or mechanical pulp.

Tl16 cooking operation, as above stated, renders the intercellular cementitious material readily friable and after crushing and pulpin the same or any desired proportion thereof ean be washed out of the pulp. The cementitious material, itself, is a fine, nonsticky material of undetermined chemical Application filed April 16,

1924. Serial No. 706,997.

composition. Sizing may be added, for instance, 1B the beater, and if desired, a portlon of the cementitious material can be Washed out, for instance during the beating operation, or after the beating operation.

For full details of the preferred procedure,

I refer to my copending cases as follows:

Serial. No. 407,759, filed. Sept. 2, 1920; Serial No.595,215, filed Qct. 13, 1922; Serial No. 616,610, filed Feb. 2, 1923; Serial No.

616,609, filed Feb. 2, 1923; Serial No. 685,895, filed Jan. 12, 1924; Serial No. 685,896, filed J an. 12, 1924; Serial No. 702,442, filed March 27221924; Serial No. 702,688, filed March 28, 19 4.

The products referred to in the present case, and forming the subject matter of the I productclaims of the present case, are particula rly those made by using as the digestive liquor, solutions containing salts of sodium, magnesium, aluminum, potassium or calcium, although to some extent the products produced when using iron sulfate and other salts as above referred to are also included. In

all of the above processes, the cooking operation converts the intercellular cementitious.

material of the raw stock (wood or other form of plant growth) into a friable condition, Without converting the material to a pulp, but I call attention to the fact that, in, my processes above referred to, the intercellular cementitious material is not dissolved during the process, nor is the lignin dissolved or substantially removed from the fibro-cellulose. Apparently the lignin is not substantially altered in my processes. Accordingly, the subsequent treatment, for instance in the pulper, liberates the intercellular cementitious material in the form of a fine non-adhesive powder which passes into suspension while the fibres of cellulose retain their original outside sheath or covering of lignin, rigidly attached thereto.

The material can be taken from the digester directly to the pulper, or to the beater modes of procedure are open, thus the material can then be directly sheeted, or it can be sized and then sheeted at slow speed, or it can be washed and then formed, for instance into sheets at rapid speed, or it can be washed and beaten for a further period of say half an hour or an hour and then sheeted or sized and then shccted. Formaking paper, this latter procedure is to be recommended. The beaten pulp, whether washed or not, can be run onto the wire cloth of a or pressed pulparticles, the pulp can be growth.

washed or used in the unwashed state, as desired.

Itis rather remarkable that even after beating for onl fifteen minutes or so, with the roll raised fi'om three to six turns above the bed, the pulp will be found to be substantially free from shives, so that it can be directely sheeted into paper, or otherwise molded. Such a product, if made into paper, will be found to have a strength substantially equal to that of grades of graft paper, and this material in the unwashed state will be hereinafter referred to as plastic wood or plastic plant growth and consists of substantially all of the original wood or plant growth, namely, it contains everything except the water-soluble constituents of the original plant growth or wood under treatment. During the beating operation, the individual fibres will be entirely separated, as is shown by the fact that the material will be free from shives and will include, in addition'to the fibro-cellulose, practically the whole of the lignin, this latter being in the form of a sheath or coating surrounding each individual fibre. The material will also contain practically the whole of the intercellular cementitious material, the latter having been converted into a finely divided or pulverulent state during the cooking, shredding and beating operations, but none of this intercellula'r cementitious material has been dissolved, and in fact nothing has been dissolved except the watersoluble constituents of the original -plant I call attention also to the fact that when using my processes herein referred to, it is not necessary to separate the knots from the remainder of the wood. These knots reduce equally as well as the rest of the Wood.

The sizing of the material, if the size is to be added, can be conveniently performed by adding any suitable sizing materials e. g. rosin size and aluminum sulfate to the pulp in the beater, the rosin size being added first, preferably, and the beating continued for say three to ten minutes, then the aluminum sulfate added and the beating continued for a few minutes longer, after which the product will be run onto the paper machine or otherwise usedfor being converted into formed articles.

It appears that during this sizing operation, there is probably an effect produced by that portion ofthe intercellular cementitious material which has been somewhat 11ydrolyzed during the beating operation or the earlier stages, which hydrolyzed matcrial is carried in the water in the beater in the form of a colloidal suspension-solution,

which is precipitated or agglutinated upon the fibres, upon the addition of aluminum sulfate or other size-precipitant used. It is to be noted that this partially hydrolyzed material is not of a sufiiciently sticky nature to prevent the pulp from working free on the wire cloth of the paper machine, whether sizing materials are added or not.

The rosin size, if used, may be that ordi-,.

narily employed, or if desired, a .small amount of dextrin or rubber latex or other emulsified gummy, waxy, resinous, orasphaltic oleaginous material can be added. Thus for instance, 100 pounds of rosin can be saponified with a few pounds of caustic soda, in the usual manner, and to the liquids thereby produced, there may be added. say

ten pounds of 33% rubber latex, or an equivalent amount of the otheremulsifiable materials above noted, to form a stock solution of size. An amount of this solution corresponding to A; to 5% of rosin, (based upon the dry weight of the wood or other vegetable material) can be added to the pulp in the beater, the beater then run for a few minutes, say 10 to 20 minutes, and then the equivalent quantity of aluminum sulfate (or alum) solution added, and the beating continued for some minutes longer. The col-- loidally suspended particles are thereby precipitated and a glutinated upon the fibres, w ich causes t e pulp to work very freely vupon the wire gauze of the paper machine,

withoutany tendency to stick or to gum up the meshes of the gauze.

If it is desired to wash out a portion of the intercellular cementitious material, (an operation which can be conjunctive with the beating) the amount to be washed out would naturally depend upon the characterof the original stock under treatment, and the amount of this intercellular cementitious material which is to be left in the final sheet, and ordinarily, about one half to three quarters of 'the intercellular .cementitious matter performed when it is desired to produce a stronger and more elastic product, and particularly when it is desired to form superior water-proofed or sized products.

An important point in connection with the sizing, is the uniform distribution of the positive colloids as those of the hydrolized or partially hydrolized intercellular cementitious material, throughout the body of the pulp, thereby balancing the negativecolloids of the cellulose and rosin.

An important point to be noted is the high strength, even in the case of the plastic wood or other plant growths, the sheets be-- ing of a strength at least approximately as great as the strength of first quality of, kraft paper of like thickness. This strength can ,be and is very greatly increased, by washing out a portion of the intercellular cementitious material as above referred to, and can also be increased by sizing.

I call attention to the fact that in the processes of the applications above referred to, the digestive or cooking treatment does not remove fromthe wood or other fibrous material, any of the water-insoluble materials, such as the lignin and intercellular cementitious material, the lignin being left in its original condition (as a sheath surrounding each cellulose fibre) and .the intercellular cementitious material simply rendered friable in the cooking operation, so that the cooked pieces of material retain their original size and shape, but are readily mashed or crushed when in the wet state by rollers or like devices.

Reference has been'made above to the fact that the cooking or digesting operation does not dissolve the intercellular cementitious material, but renders this readily friable. Hence when the cooked material is crushed or mashed (in a wet state) the said inter; cellular material is converted into a fine powder, which readily becomes suspended in the water present at that stage or added subsequently. This fine powder is non-adhesive, and hence does not cause objectionable sticking of the material to the wire cloth of the paper machine. The portion of this intercellular material which is washed out of the pulp can be allowed to settle out of the water, and forms a valuable by-product.

I further call attention to the fact that the plant growths or wood can be treated" in the form ofpieces much larger than the ordinary size of chips. 1 The pulp products (either sheets or other molded articles) produced in accordance with the present process are usually of 'a more or less brownish color, the exact shade will depend largely upon the particular rawmaterial under treatment. Thus when using spruce wood, the plup will be found to have a light bufl' color, whereas when usin some of the other kinds of wood such as t e gums, a substantially darker color, approaching a dark brown will be produced. While the pulp may be bleached, by methods well understood in the art, it is (for many purposes) not necessary to bleach it, for instance in producing brown wrapping paper, the unbleached pulp is entirely suitable, and the unbleached. pulp products retain their full strength. I

The products of the present case are clearly distinguished from the soda pulp,.sulfito In my U. s. Patent- 1,04e,475, I have described and claimed the use of a digestive solution containing zinc chlorid,; glycerin and tannic acid.- The said process converts a part of the lignin and intercellular cementitious material into a sticky paste-like material, probably amyloid, while in the process of the copending cases above referred to, no sticky paste-like material is formed, and the liberated intercellular cementitious matter is non-sticky.

In my U. S. Patent No. 1,166,848, I have described a process in which zinc sulfate is used, preferably with gylcerin and tannic acid, with or without zinc chlorid, as the digestive solution. -This process also converts some part of the intercellular cementitious material into a somewhat sticky or semi-gelatinous state. 3

In both of the above patented processes, the pulp, even after the ordinary washing or even after considerably more washing than would be commonly used in making paper, still contains readily detectable amounts of zinc compounds. There appears to be some insoluble zinc compounds (perhaps resinates) formed, which become attached to, or even may pass into the hollow interiors of the fibres, and cannot be readily washed out.

- The zinc salts, when used as the sole. or.

the major part of the inorganic dissolved weakening. This latter action is obviously slow, but is apparently somewhat accelerated by changes in the 'humidit -content of the paper, pulp or other nished articles.

Sheets of product made in accordance with the first mentioned patent, and stored for over ten years, are found to have only a fraction of their original strength. Products made in accordance with some of the above mentioned cases, and tested annually for five years, show that the products retain their strength far better than the products made when using zinc compounds.

The products made by the two prior patents are generally somewhat more deeply colored than are the products of the copending cases above referred to, the individual fibres of the products of the said prior patents seem to be more impregnated with coloring matter than the fibres in the products of the copending cases above noted.

The products of the said two prior patents (especially the earlier) seem to undergo more oxidation in storage, than is the case with the products herein claimed. For the reasons above stated, I prefer to avoid the presence of zinc compounds in the products.

The products of the present case are particularly to be distinguished from the products of my two prior patents by the last six paragraphs above written.

I claim:

1. A sheet of plastic plant growth, containing substantially the full water-insoluble content of the plant growth, including the lignin, fibro-cellulose and intercellular cementitious material, the individual fibers being entirely separated and each having its outside individual sheath of lignin, the fibers being substantially of uniform type throughout the sheet, and the individual fibers being substantially unbroken and of natural shape and size, such product being free from zinc compounds and being substantially stronger than any kind of mechanical pulp.

2. A sheet of plastic wood, containing substantiallythe full Water-insoluble content of the wood, including the lignin, fiblO-CGll11-' lose and intercellular cementitious material, the individual fibers being entirely separated and each having its outside individual sheath of lignin, the fibers being substantially of uniform type throughout the sheet, and the individual fibers being substantially unbroken and of natural shape and size, such sheet being substantially stronger than 'a sheet of mechanical pulp of the same thickncss.

3. A sheet of plastic plant growth, containing substantially the full water-insoluble content of the plant growth, including the lignin, fibro-cellulose and intercellular cementitious material, the individual fibers being entirely separated and each having its outside individual sheath of lignin, the fibers being substantially of I uniform type throughout the sheet, and the individual fibers being substantially unbroken and of natural shape and size, such sheet being of a strength at least approximately as great as good quality of kraft paper of like thickness, and such product retaining its full strength if stored for several years.

4. -A shaped article of plastic plant growth containing the full content of fibro-cellulose and lignin, together with a portion of the intercellular cementitious material of the raw stock, the individual fibers being entirely separated and each having its natural individual sheath of lignin, and the fibers being of their natural size, length and shape, such article being free from zinc compounds and substantially stronger than a like article formed of ground-wood pulp.

5. A molded structure of plastic plant growth, including lignin, fibro-cellulose and a part at least of the intercellular cementitious material of the raw stock, the individual fibers being entirely separated and each having its individual sheath of lignin on its I outside, the fibers being of substantially uniform type throughout the structure and the individual fibers being substantially unbroken, and of natural length and strength, and free from zine compounds and said structure having greater strength than a similar structure composed of, mechanical pulp.

6. A water-resistant and permanently sized sheet composed essentially of clear cut separated fibers of fibro-cellulose each with its outside sheath of lignin and agglutinated with intercellular cementitious material and sizing material, the individual fibers being of substantially their original length and strength, and such product containing a part at least of the intercellular cementitious material of the raw stock, such product being free from zinc compounds and of a far greater strength than a similar sheet of any kind of mechanical pulp.

In testimony whereof I afiix my signature.

ROBERT A. MARR. 

